RYR1 and myopathy: Patient 522 has clear signs of myopathy and a clinical picture milder than that of patients 425 and 521, who are composite heterozygous for RYR1 c.9293G>T (p.S3098I) and c.14771_14772insTAGACAGGGTGTTGCTCTGTTGCCCTTCTT (p.F4924_V4925insRQGVALLPFF).